diff --git a/tests/client/client_common.py b/tests/client/client_common.py
index 7037b791..15a8d8ba 100644
--- a/tests/client/client_common.py
+++ b/tests/client/client_common.py
@@ -260,6 +260,16 @@ def test_delete_image__not_only_meta_ok(ebnt: Ebonite, image_to_delete: Image, m
     assert ebnt.meta_repo.get_image_by_id(image_to_delete.id) is None
 
 
+def test_get_default_environment(ebnt: Ebonite):
+    ebnt.default_env = 'Pseudo_env'
+    env = ebnt.get_default_environment()
+    assert env == 'Pseudo_env'
+
+    ebnt.default_env = None
+    ebnt.get_default_environment()
+    assert ebnt.get_environment('docker_localhost') is not None
+
+
 @docker_test
 def test_build_and_run_instance(ebnt: Ebonite, regression_and_data, container_name, mock_env):
     reg, data = regression_and_data
diff --git a/tests/core/objects/test_core.py b/tests/core/objects/test_core.py
index bd5625c9..5a00b644 100644
--- a/tests/core/objects/test_core.py
+++ b/tests/core/objects/test_core.py
@@ -3,11 +3,13 @@
 from pyjackson import deserialize, serialize
 from pyjackson.core import Unserializable
 
-from ebonite.core.errors import (EboniteError, MetadataError, NonExistingModelError, NonExistingTaskError,
+from ebonite.core.errors import (EboniteError, MetadataError, NonExistingEnvironmentError, NonExistingModelError,
+                                 NonExistingPipelineError, NonExistingProjectError, NonExistingTaskError,
                                  UnboundObjectError)
 from ebonite.core.objects import ModelWrapper
 from ebonite.core.objects.artifacts import Blobs, InMemoryBlob
-from ebonite.core.objects.core import Model, Pipeline, Project, Task, _WrapperMethodAccessor
+from ebonite.core.objects.core import (Model, Pipeline, PipelineStep, Project, RuntimeEnvironment, Task,
+                                       _WrapperMethodAccessor)
 from ebonite.core.objects.dataset_source import DatasetSource
 from ebonite.core.objects.metric import Metric
 from ebonite.core.objects.requirements import InstallableRequirement, Requirement, Requirements
@@ -93,6 +95,18 @@ def test_project_serde(project_saved):
     serde_and_compare(project_saved)
 
 
+def test_task_wo_project(task_saved):
+    task_saved.project_id = 666
+    with pytest.raises(NonExistingProjectError):
+        task_saved.project
+
+
+def test_task_delete_nonexistant_pipe(task_saved):
+    pipe = Pipeline(id=666, name='pipe', steps=[PipelineStep('a', 'b'), ], input_data=str, output_data=str)
+    with pytest.raises(NonExistingPipelineError):
+        task_saved.delete_pipeline(pipe)
+
+
 def test_task__project_property(project_saved_art, task):
     assert project_saved_art.has_artifact_repo
     assert project_saved_art.has_meta_repo
@@ -179,6 +193,9 @@ def test_task__delete_model_with_artifacts(task_saved, model, artifact_repo):
     assert model.id is None
     assert model.task_id is None
 
+    task_saved.unbind_artifact_repo()
+    assert task_saved.has_artifact_repo is False
+
 
 def test_task__delete_model__nonexistent(task_factory, model):
     model_task = task_factory(True)
@@ -239,6 +256,8 @@ def test_task__delete_metric_non_existing(task_saved):
 
 
 def test_task__add_dataset(task_saved, dataset):
+    assert task_saved.has_dataset_repo is True
+
     task_saved.add_dataset('data', dataset)
     assert 'data' in task_saved.datasets
     assert isinstance(task_saved.datasets['data'], DatasetSource)
@@ -250,6 +269,9 @@ def test_task__add_dataset(task_saved, dataset):
     assert isinstance(task.datasets['data'], DatasetSource)
     assert not isinstance(task.datasets['data'], Unserializable)
 
+    task_saved.unbind_dataset_repo()
+    assert task_saved.has_dataset_repo is False
+
 
 def test_task__add_dataset_exists(task_saved, dataset):
     task_saved.add_dataset('data', dataset)
@@ -449,6 +471,15 @@ def f2(a):
     return model
 
 
+def test_pipeline_wo_task(meta, len_model, task_saved):
+    pipeline = len_model.as_pipeline()
+    pipeline.task_id = task_saved.id
+    pipeline = meta.create_pipeline(pipeline)
+    pipeline.task_id = 666
+    with pytest.raises(NonExistingTaskError):
+        pipeline.task
+
+
 def test_pipeline__append(double_model, len_model):
     p1 = double_model.as_pipeline()
     p2 = p1.append(len_model)
@@ -548,6 +579,29 @@ def test_task__delete_pipeline(task_factory, pipeline_factory):
 
 
 # ################IMAGES###########
+def test_image_wo_task(meta, image_factory, task_saved):
+    image = image_factory()
+    image.task_id = task_saved.id
+    image = meta.create_image(image)
+    image.task_id = 666
+    with pytest.raises(NonExistingTaskError):
+        image.task
+
+    with pytest.raises(UnboundObjectError):
+        image.environment
+
+    env = RuntimeEnvironment('env')
+    env = meta.create_environment(env)
+
+    image_2 = image_factory()
+    image_2.task_id = task_saved.id
+    image_2.environment_id = env.id
+    image_2 = meta.create_image(image_2)
+    image_2.environment_id = 666
+    with pytest.raises(NonExistingEnvironmentError):
+        image_2.environment
+
+
 def test_task__no_images(task_factory):
     task = task_factory(True)